Phenotypic and Genotypic Screening of Extended-Spectrum Beta-Lactamase-Producing Escherichia Coli Isolated from a Sample of Patients with Community-Acquired Urinary Tract Infection

The bacteria Escherichia coli is the most common community-acquired urinary tract infection (UTI) pathogen, which is responsible for 75%–95% of cases, and due to the extensive use of β-lactam antibiotics in clinical cases, Extended- spectrum beta-lactamase (ESBLs) producing Escherichia coli have emerged. This study was done to isolate and identify Escherichia coli in a sample of Iraqi patients with a community- acquired urinary tract infection (CA-UTIs), the ESBL-producing E. coli was characterized phenotypically and genotypically. About 120 urine samples were collected from September 2022 to February 2023 from UTI patients including males and females. The isolates were tested against 17 antibiotics by using the disc diffusion method. The double disc synergy test (DDST) was used to identify ESBL-producing E. coli isolates among the isolates. ESBL-producing E. coli isolates were tested to characterize the predominant beta-lactamase genes by real-time PCR using specific primers for encoding genes (TEM, CMY, SHV, and CTX- M). Out of 120 cases, the total isolated E. coli was (36) 30%. Sensitivity tests against 17 antibiotics showed high resistance to Rifampin (97.8%), Neomycin (97.4%), Ceftazidime (96.8%), Piperacillin (92.09%), Cefotaxime (91.73%), Ceftriaxone (90.32%) and Ciprofloxacin (89%). Whereas, a high degree of susceptibility among the tested isolates was toward Meropenem (82.73 %), then Imipenem (79.58%) followed by Cefoxitin (79.58%). The double disc synergy test (DDST) was used to identify ESBL-producing E. coli isolates. Out of 36 isolates, 9 (25%) showed positive DDST results and were thus identified as ESBL producers. A Real-time PCR assay showed, that 6 (66.6%) isolates out of 9 had blaTEM + blaCMY + blaSHV + blaCTX-a and blaCTX- b, and 2 (22.2) isolates had had blaTEM + blaCMY + blaCTX-a and blaCTX-b, and One isolate 1 (11.1%) had blaTEM + blaCMY + blaCTX-a. The drugs of choice among the resistant isolates in our tested group were meropenem, imipenem, and cefoxitin.